I have a maxum 1999, scr 300, 5.0 carberated. At idle speed, 800 rpm, the tach and volt meter will twitch down. After first getting on plane , 3400 rpms , the tach will drop 600 rpms and back up to 3400 rpms very quickly. After that it runs fine. Alternator has been checked and ground wires tightened. Any suggestions
